Baseline levels of serum CCL5 pre-infection (day 0) were the same for WT C57BL/6 mice and their congenic “sash” mutants, whereas, beyond day 1, CCL5 levels were significantly lower in the MC-deficient mutant, both statistically as well as in biologically relevant quantity, until the difference was leveled on day 4, though at values still significantly above the pre-infection levels. The gene discussed is CCL5; the disease is infection.